Last month he was under fire after it was revealed he had used a tax avoidance scheme to receive a loan of more than £18,000 while working as a manager in the energy industry.

Earlier in the year the MP had been pressing the Treasury to close loopholes to prevent tax avoidance.

There was no suggestion he had acted illegally, but now the Parliamentary Commissioner for Standards has confirmed an investigation will take place after a complaint by Paul McGarry, a Lib Dem candidate for this year’s Scottish Parliament elections.

This concerns a claim that Mr Boswell failed to record in the parliamentary register that he was a director of a company, Boswell and Johnston Limited.

Mr Boswell could not be contacted for comment.

Since May two newly-elected MPs, Michelle Thomson (Edinburgh West) and Natalie McGarry (Glasgow East), have withdrawn from the SNP whip while separate probes into alleged cash irregularities take place.

Councillor McCabe stressed he did not wish to “judge” Mr Boswell, but added: “This situation stinks of hypocrisy and he should consider his position as an MP.

“He said he was strongly opposed to tax avoidance, but was then found to be participating in it himself.

“He seems to have used his position. You can’t tell people to do one thing and do another yourself.”